1. Field of the Invention
The present invention relates to magnetic tape driving apparatuses. Specifically, the present invention relates to magnetic tape driving apparatuses that employ a magnetoresistance effect-type (MR) head, magnetic tape driving apparatuses that record various information to a high-capacity magnetic tape such as a computer tape, and magnetic tape driving apparatuses that are capable of reproducing various information that is recorded to a high-capacity magnetic tape.
2. Description of Related Art
Recently, there has been an increase in users that record (backup) a copy of data recorded to a hard disk installed in a computer to magnetic tape. In the field of magnetic tape for data backup, with the increasing capacity of hard disks, magnetic tape that has a recording capacity of several 100 gigabyte to several terabyte per roll of tape has been commercialized. In the future, in order to be compatible with further increased hard disk capacity, increased capacity of magnetic tape for data backup will be necessary.
In order to increase the capacity of magnetic tape, it is necessary to increase the linear recording density of magnetic tape. In order to increase the linear recording density of magnetic tape, it is necessary to finish the magnetic layer surface of the magnetic tape so as to be very smooth. However, when the magnetic layer surface of the magnetic tape is smoothly finished, there is a tendency for abrasion of the magnetic layer to decrease.
In this sort of a magnetic tape driving apparatus that performs recording and reproduction using magnetic tape, an MR head is often used in order to detect very small magnetic flux with short wavelength. In magnetic tape that has been recorded to at high density, magnetic flux is very small and has short wavelength. Accordingly, when a slight stain is affixed to the surface of the magnetic head, spacing increases between the surface of the magnetic head and the magnetic layer surface of the magnetic tape, reproduction output decreases due to a change in the bias magnetic field, and so there are problems such as that reproduction errors occur, increasing the error rate. This sort of phenomenon occurs markedly in a low humidity environment, and therefore is a significant problem.
Patent Document 1 (JP H5-81622A) discloses a configuration in which a magnetic head is provided with a cooling mechanism, with the object of improving magnetic recording properties. By adopting such a configuration, it is possible to avoid deterioration of the magnetic head or magnetic tape caused by heat generated by sliding.
Patent Document 2 (JP H8-45026A) discloses a method for increasing the sense current of an MR element, thus improving reproduction output.
The configuration disclosed in Patent Document 1 performs temperature control so as to start cooling when the temperature of the face opposing the magnetic recording medium of the magnetic head becomes increased relative to the other end. With the configuration disclosed in Patent Document 1, it is possible to avoid deterioration of the magnetic head and magnetic recording medium caused by heat generated by sliding, but no effects are exhibited with regard to increasing error rate due to staining in a low humidity environment.
With the configuration disclosed in Patent Document 2, Joule heat caused by the flow of sense current through the MR head is decreased, and by increasing the limited sense current it is possible to improve magnetic recording properties. However, no effects are exhibited with regard to increasing error rate due to staining in a low humidity environment.
On the other hand, with a magnetic tape driving apparatus, in a high humidity environment, the friction coefficient of the tape sliding face of the magnetic head is high, so it is difficult to keep a constant sliding speed of the magnetic tape. Thus, the magnetic head cannot properly read information from the magnetic tape, so a problem such as increased error rate occurs.
Patent Document 3 (JP H6-44515A) discloses a configuration in which the tape sliding face of the magnetic head is coated with a material having good wettability. However, with the configuration disclosed in Patent Document 3, because temperature and humidity are not monitored, it is difficult to keep a constant humidity of the magnetic head.
Patent Document 4 (JP S62-146447A) discloses a configuration in which temperature and humidity of the magnetic head are monitored. However, because a case of a video tape recorder in which a cylinder in which a magnetic head is provided and a humidity sensor are disposed is comparatively large, there is variation of the temperature and humidity within the case, so it is difficult to control the humidity. Accordingly, when used in a high humidity environment, it is possible that a phenomenon will occur in which the magnetic tape sticks to the magnetic head.